Method for stacked elution of mother-daughter radionuclides

Abstract

A method for enhancing radionuclide activity of a daughter radionuclide-containing eluate obtained from a mixture of mother/daughter radionuclides is disclosed. This method comprises i) contacting separation particles with an aqueous solution containing a mixture of mother and daughter radionuclides wherein daughter radionuclides bind to separation particles and mother radionuclides does not. That contact is maintained ii) for a time for unbound daughter radionuclide to bind to the separation particles. Unbound mother radionuclide is iii) separated from the daughter radionuclide-bound separation particles using a washing solution. Steps i) and ii) are repeated at least once iv). The bound daughter radionuclide is stripped v) from the separation particles using a volume of stripping solution less than that used if only steps i), ii), iii) and v) were used for each of the recited at least two separations to form an aqueous eluate having enhanced daughter radionuclide activity.

1 . A method for enhancing the radionuclide activity of a desired daughter radionuclide-containing aqueous eluate that comprises the steps of
 i) contacting a separation medium with an aqueous solution containing a mixture of mother radionuclide and desired daughter radionuclide, wherein said desired daughter radionuclide has a high affinity for and binds to said separation medium and said mother radionuclide has a low affinity for and does not bind to said separation medium to form a dispersion containing at least water, separation medium, desired daughter radionuclide, separation medium-bound to said desired daughter radionuclide, and unbound mother radionuclide;   ii) maintaining that contact for a time period sufficient for unbound desired daughter radionuclide to bind to the separation medium;   iii) separating said unbound mother radionuclide from the desired daughter radionuclide-bound separation medium formed in step ii) using a washing solution;   iv) repeating steps i) and ii) at least once and up to the binding limit of the desired daughter radionuclide to the separation medium used; and   v) stripping the bound desired daughter radionuclide from the separation medium using a volume of stripping solution less than that used if only steps i), ii), and iii) were used for each of the recited at least two separations to form an aqueous eluate solution having enhanced desired daughter radionuclide activity.   
     
     
         2 . The method according to  claim 1 , wherein said desired daughter radionuclide is Tc99m present as TcO 4 -1, or Re188 present as ReO 4 -1. 
     
     
         3 . The method according to  claim 2 , wherein said separation particles comprise particles having a plurality of covalently bonded —X—(CH 2 CH 2 O)n-CH 2 CH 2 R groups, wherein X is O, S, NH or N—(CH 2 CH 2 O)m-R 3 , where m is a number having an average value of zero to about 225, n is a number having an average value of about 15 to about 225, R 3  is hydrogen, C 1 -C 2  alkyl, 2-hydroxyethyl or CH 2 CH 2 R, and R is selected from the group consisting of —OH, C 1 -C 10  hydrocarbyl ether having a molecular weight up to about one-tenth that of the —(CH 2 CH 2 O)n-portion, carboxylate, sulfonate, phosphonate and —NR 1 R 2  groups where each of R 1  and R 2  is independently hydrogen, C 2 -C 3  hydroxyalkyl or C 1 -C 6  alkyl, or —NR 1 R 2  together form a 5- or 6-membered cyclic amine having zero or one oxygen atom or zero or one additional nitrogen atom in the ring, said separation particles having a percent CH 2 O/mm 2  of particle surface area of greater than about 8000 and less than about 1,000,000. 
     
     
         4 . The method according to  claim 2 , wherein said mother radionuclide of said desired daughter radionuclide Tc99m is present as MoO 4 -2. 
     
     
         5 . The method according to  claim 2 , wherein said mother radionuclide of said desired daughter radionuclide Re188 is present as WO 4   −2 . 
     
     
         6 . The method according to  claim 1 , wherein said desired daughter radionuclide is Ac225 present as Ac +3 . 
     
     
         7 . The method according to  claim 6 , wherein said mother radionuclide of said desired daughter radionuclide Ac225 is present as Ra +2 . 
     
     
         8 . The method according to  claim 6 , wherein said Ra +2  is one or both of Ra225 and Ra226. 
     
     
         9 . The method according to  claim 6 , wherein said separation particles comprise a diglycolamide extractant corresponding in structure to Formula I dispersed onto a porous inert resin or 
       
         
           
           
               
               
           
         
       
       silica support, wherein R 1 , R 2 , R 3  and R 4  are the same or different and are hydrido or hydrocarbyl groups such that the sum of carbon atoms of R 1 +R 2 +R 3 +R 4  is about 14 to about 56. 
     
     
         10 . The method according to  claim 1 , wherein said desired daughter radionuclide is Ga68 present as Ga +4 . 
     
     
         11 . The method according to  claim 8 , wherein said mother radionuclide of said desired daughter radionuclide Ga +4  is present as Ge +4 . 
     
     
         12 . The method according to  claim 11 , wherein said separation particles comprise a strongly basic anion exchange resin with quaternary ammonium functional groups attached to the styrene divinylbenzene copolymer lattice cross-linked with about 2 to about 12 wt % of divinylbenzene. 
     
     
         13 . In a method for enhancing the radionuclide activity of a desired daughter radionuclide-containing aqueous eluate separated from an aqueous composition containing a mother radionuclide and a daughter radionuclide in which said aqueous composition is 1) contacted with a separation medium in which said desired daughter radionuclide has a high affinity for and binds to said separation medium and said mother radionuclide has a low affinity for and does not bind to said separation medium to form a dispersion containing at least water, separation medium, desired daughter radionuclide, separation medium-bound to said desired daughter radionuclide, and unbound mother radionuclide, 2) that contact is maintained for a time period sufficient for unbound desired daughter radionuclide to bind to the separation medium, 3) the unbound mother radionuclide is separated from the desired daughter radionuclide-bound separation medium formed in step 2) using a washing solution, and 4) the bound desired daughter radionuclide is stripped from the separation medium using a volume of stripping solution to form an aqueous eluate, the improvement that comprises repeating steps 1), 2), and 3) at least once thereby forming an aqueous eluate solution containing enhanced desired daughter radionuclide activity in a stripping solution eluate volume that is less than that used if only steps 1), 2), 3) and 4) were used for each of the recited at least two separations. 
     
     
         14 . The method according to  claim 13 , wherein said desired daughter radionuclide is Tc99m present as TcO 4   −1 , or Re188 present as ReO 4   −1 . 
     
     
         15 . The method according to  claim 14 , wherein said mother radionuclide of said desired daughter radionuclide Tc99m is present as MoO 4   −2 . 
     
     
         16 . The method according to  claim 13 , wherein said mother radionuclide of said desired daughter radionuclide Re188 is present as WO 4   −2 . 
     
     
         17 . The method according to  claim 13 , wherein said desired daughter radionuclide is Ac225 present as Ac +3 . 
     
     
         18 . The method according to  claim 17 , wherein said mother radionuclide of said desired daughter radionuclide Ac225 is present as Ra +2 . 
     
     
         19 . The method according to  claim 18 , wherein said Ra +2  is one or both of Ra225 and Ra226. 
     
     
         20 . The method according to  claim 13 , wherein said desired daughter radionuclide is Ga68 present as Ga +4 . 
     
     
         21 . The method according to  claim 20 , wherein said mother radionuclide of said desired daughter radionuclide Ga +4  is present as Ge +4 .